Mobile drfating apparatus with replaceable units



c. E. JUSTIS 7 3,106,783 MOBILE DRAFTING APPARATUS WITH REPLACEABLE UNITS Oct. 15, 1963 Filed Aug. 21, 1958 2 Sheets-Sheet l F l G. 4

INVENTOR. Charles E. Justis g lhwm1m ATT'VJ Oct. 15 1963 (3. E. JUSTIS ,1

MOBILE DRAFTING APPARATUS WITH REPLACEABLE UNITS 2 shee s-sheet 2 Filed Aug. 21. 1958 FIG? ii e7 INVENTOR. Charles E.Justis BY F|G.|3 Z 5 ryimy arn United States Patent 0 3,106,783 MOBILE DRAFTINS- APPARATUS WITH REPLACEABLE UNITS Charles E. Justis, 5t Stratford Ave., Clifton Heights P.0., Aidan, Delaware County, Pa. Filed Aug. 21, 1958, Ser. No. 756,480 1 Claim. (Ci. 338tl) This invention relates generally to the class of geometrical instruments and is directed more particularly to drafting apparatus of the type disclosed in my issued Patent No. 2,804,691 of September 3, 1957.

The apparatus disclosed in the above identified patent is of the type involving a straight edge which is associated with a means connecting it with a supporting drawing board or other surface, whereby such straight edge may be easily moved back and forth relative to the Working surface of the drawing board for the purpose of drawing or laying out parallel lines thereon.

As stated in the patent referred to, mobile drafting apparatus designed prior to my patented structure involved the employment of certain structural features which have proved, in practice, to be unsatisfactory and which, because of their structure, developed after a period of use irregularities in connection with the movement of the straight edge and it was accordingly an object of that invention to provide an operatively effective mobile drafting apparatus characterized by such refinements which would insure positive action free of the drawbacks inherent in prior devices.

It is, of course, recognized as of utmost importance that a straight edge for any use particularly in connection with the drafting of plans, must be of a construction and material which will not become distorted by reason of atmospheric conditions or by reason of constant use, or which will not lose the smoothness of its edge and in mobile apparatus such as the present invention is directed to, it is important that the means employed for insuring the accurate placement of the straight edge on the drawing surface when moved thereover relative to previously applied lines be such that it cannot easily get out of adjustment.

While the mobile apparatus of the present invention employing a straight edge as a part of the construction thereof is designed to give maximum service, it will nevertheless be realized that after a period of use wear will occur and also as a result either of accident or careless handling, parts of the device may become damaged in some way and accordingly it is an object of the pres ent invention to provide a new and novel mobile drafting apparatus of the character stated wherein the construction is such that in the event of replacement becoming necessary of the straight edge itself due to wear or some other part due to accident, it will not be necessary to replace the entire apparatus but replacement may be made of the blade of the straight edge only or of certain of the other parts such as those elements associated with the blade by which the latter is coupled with the drawing board to facilitate its movement in the desired manner thereover.

It is a further object of the present invention to provide a mobile drafting apparatus of the character above referred to wherein the blade of the straight edge, in one embodiment of the invention, may be formed of a relatively light weight more or less flexible material such as synthetic resin plastic and made strong and rigid to prevent easy distortion, by means of a rigid back rib of metal or other suitable material combined with the blade in a novel manner, whereby the blade and the stiffening back rib may be separated if and when necessary as, for example, if it should happen that the blade might have to be replaced due to wear or damage to the straight edge portion thereof.

Still another object of the invention is to provide in apparatus of the character stated, a blade having cord pulleys rotatably mounted upon the ends thereof for coaction with a flexible guide cord secured to a drawing board and passing across the pulleys and in crossed relation in and through a tubular rib carried by the blade, wherein such cord pulleys are mounted in a protective housing which, in addition to its function of guarding the cord pulleys so that the same will not be accidentally knocked out of position or adjustment, is detachably coupled to the top of the blade in such a way that it may be readily replaced if and when necessary.

A further object of the invention is to provide in a structure of the character hereinabove set forth, apparatus wherein the blade, the reinforcing rib extending lengthwise of the back thereof, and the cord pulley housing are all separably coupled together so that any one thereof may be replaced if such replacement should be required.

A still further object of the invention is to provide in a mobile apparatus of the type shown in my issued patent, wherein gear Wheels are carried upon the ends of the blade for coaction with toothed racks secured to the drafting board, a novel construction for mounting each pair of gears upon an end of the straight edge blade whereby such gears, being enclosed in a protective housing, can be separated as a unit with the housing from the end of the blade for ready replacement.

Other objects and advantages of the invention will become apparent as the description of the same proceeds and the invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing with the understanding that the invention is not confined to a strict conformity with the showing of the drawings but may be changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings:

FIG. 1 is a view in perspective illustrating one embodiment of the present mobile straight edge mechanism and showing the same in working position upon a drawing board and overlying a paper sheet thereon;

FIG. 2 is a sectional view on an enlarged scale taken substantially on the line 22 of FIG. 1 through the straight edge structure only;

FIG. 3 is a view in side elevation of one end of the straight edge structure;

FIG. 4 is a horizontal section taken substantially on the line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken substantially on the line 55 of FIG. 3 through the straight edge blade body and the reinforcing rib only;

1G. 6 is a view in perspective of another embodiment of the straight edge mechanism showing the same applied to a drawing board and overlying a sheet of paper on the board;

FIG. 7 is a partial transverse section taken substantially on the line 7-7 of FIG. 6;

FIG. 8 is a section taken substantially on the line 8-8 of FIG. 7;

FIG. 11 is a view in end elevation of a straight edge blade and reinforcing in one piece; and

back rib of tubular form molded FIG. 12 is a diagrammatic view illustrating the manner of positioning one of the two pulleys shown in FIGS. 2 and 4 for most effective engagement of the retaining strand thereon.

FIG. 13 is a partial section taken across the inner wall of the gear wheel box and illustrating the angulated reinforcement bracket attached thereto.

FIG. 14 is a view illustrating an end elevation of another embodiment of the straight edge showing the reinforcement rib as tubular and secured to the top of the blade body.

Referring now more particularly to the drawings, numeral in FIG. 1 illustrates a conventional drafting board upon which is shown a paper sheet which is designated 12 and the first described embodiment of the invention is designed to be coupled with tensioned single strand elements 14 which are attached to the drawing board 10 at the corners thereof by means of suitable fastening elements 16 such as thumb tacks or the like and which work over pulleys and through the hollow reinforcing back rib of the straight edge blade in the manner hereinafter described.

The straight edge blade construction shown in FIG. 1 to 5 is generally designated 18. In this embodiment of the invention the blade body is designated 20 and as shown in FIG. 2, is of substantial width and is formed with a transversely bowed or arched under surface 22 while the top is tapered as indicated at 24 to provide the relatively thin guiding edge 25. Extending transversely of the top of the blade 20 is the stiffening or reinforcing rib 26. This rib in the embodiment of the invention under description is preferably tubular and may be formed of a suitable metal such as aluminum or the like and when formed of such metal it may be extruded in the shape shown in cross section in FIG. 5 providing the flat top 27 and the side walls 28 in slightly downwardly convergent relation with the bottom plate or bottom wall portion 29 which extends slightly beyond the side walls 28 forming laterally projecting longitudinal corner ribs 30. In this construction the blade body is provided with the longitudinal slot 31 which opens through the top of the blade body and is formed to conform to the cross sectional contour of the bottom portion of the rib 26 whereby the rib can be det-achably connected with the blade body by sliding it into the slot 31 from one end of the blade body in an obvious manner. In this construction it will be seen that the blade body may be formed of relatively light material such as synthetic resin plastic and which material may be transparent so that the user of the straight edge can see through it to facilitate the laying out of lines along the edge and the back rib 26 provides the necessary stiffness to prevent the blade from bending or twisting when in use or otherwise becoming distorted.

As previously stated, the side walls 28 slope inwardly or are convergent and extend into the body of the blade 20 forming a deep corner 28 and in order to avoid accumulation of extraneous matter in this angle, which might work down into the slot 31, there is secured in each corner or angle 28 a dust shield or stop 28 which extends the full length of the stiffening rib, as shown in FIG. 1.

The reinforcing rib 26 is of a length less than the overall length of the blade body 20 to which it is attached and there is positioned upon the top of the blade body across each end of the rib 26 a narrow box 32 which is of a length to extend beyond the sides of the rib as shown best in FIGS. 2 and 4, and is contoured to fit the inclined or tapered top surfaces 24 and the intermediate top portion of the blade. This box has the bottom 33, the top wall 34 and the inner and outer side walls 35 and 36. These latter walls, together with the top wall 34 and the bottom 33, are connected by the end walls 37. The inner wall 35 has an opening 38 centrally thereof which coincides with the adjacent open end of the rib 26 for the purpose hereinafter set forth, and in addition each of the end walls 37 has an aperture 39 for the purpose about to be described.

The bottom 33 of the box 32 is, as previously stated, shaped so as to fit the sloping or tapered top surfaces of the straight edge blade and mounted upon this bottom 33 in spaced relation longitudinally of the box are two pivot pins 48 which are inclined slightly toward the adjacent ends of the box and each of these pivot pins has rotatably mounted thereon a grooved cord pulley 41.

The box 32 is in two parts. One part comprises the bottom wall or plate 33 which is secured to the top of the straight edge blade body by screws or pins 42 extended upwardly from the under side of the blade body as shown in FIG. 3, and the second part of the box forms a removable top or cover and is made up of the walls 34, 35 and 36 and 37, and this top is removably secured in place over the bottom wall plate 33 by means of the single central screw 43 which is extended through the top wall 34 and is threaded at its lower end into the bottom wall or plate 33 between the pulleys 41. Thus it will be seen that the top of the pulley or wheel box 32 can be removed for access to the pulley wheels 41 if and when such removal becomes necessary, and the apertures 39 are positioned so that they will be in a line tangential to the sides of the pulleys nearest to the end of the straight edge while the adjacent sides of the pulleys are located so that a line tangential thereto will extend through the opening 33 into the hollow rib 26.

For maintaining the straight edge body in the desired parallel relation with the board and a paper thereon or to facilitate movement of the straight edge blade whereby parallel lines may be drawn, the two strands 14 which may be in the form of strong cords or light metal cables are connected each between two diagonally located anchoring pins -16 and each extends through an aperture 39 into one wheel box and then extends through the rib 26 to the opposite wheel box and out of the aperture 39 on the side of the latter wheel box opposite from the aperture through which it entered and around the adjacent pulley to the adjacent corner anchor pin 16. Thus it will be seen that the strands 14 extend between opposite corners of the board and across the pulleys 41 and in crossed relation through the rib 26 so that the straight edge can be shifted up and down on the drawing board and will be held parallel to the top and bottom edges of the board at all times.

Opposite side edges of the apertures 39 are bordered by the outwardly and laterally curving flanges 39 which are most clearly illustrated in FIG. 4. These flanges function as chafe guards for the cords or cables 14 in the event that in the use of the straight edge the same might be shifted transversely of the board whereby contact would be made with the edges or sides of the openings. By the provision of these curved guards 39 a rounded surface is Lhad across which the cords or cables will slide and thus be prevented from becoming damaged.

It will be seen also from the foregoing that with the arrangement illustrated and described in this first embodiment of the invention, should any of the parts he come damaged, the entire straight edge structure does not have to be discarded but the damaged part can be removed and replaced. For example, the wheel box may be opened and the pulley wheels replaced or if the edge of the straight edge body or blade should become worn or broken, as sometimes happens in the use of an instrument of this kind, the reinforcing rib 26, together with the pulleys or wheel boxes, can be taken off and applied to a new blade, thus avoiding the necessity of replacing the entire instrument.

In the diagrammatic view forming FIG. 12, the reason for slanting or tilting the pulley wheel pivot pins 40 is clearly illustrated as it will be seen that by so positioning the pivot pin the wheel will be placed in a plane which intersects the surface of the drawing board at the position or line occupied by the anchoring pin 16 for the strand .14 and thus the strand will work around the pulley smoothly without danger of slipping off.

It will be apparent from the foregoing that the top portion of the wheel box 32 engages over and extends down across the edges of the bottom plate or wall 33. In addition the outer side wall 36 is extended beyond the walls 35 and 37 to lie against or across a portion of the adjacent end face of the straight edge blade 20. By the engagement of the walls 35 and 37 against the adjacent edges of the bottom 33 and by the extension of the outer wall 36 to lie against the end of the blade body, it will be seen that the cover or removable top portion of the wheel box is easily placed in position and is rigidly held against movement or displacement by the employment of only the single attaching screw 43.

FIGS. 6 to inclusive, illustrate another embodiment of the invention wherein use is made of comparatively narrow rigid toothed-rack components in association with which wheel elements at the ends of the straight edge work for the control-led movement of the straight edge across the drawing board. In these figures the drawing board is generally designated 44 and the numeral 45 designates a sheet of paper or linen on the board across which the straight edge is disposed for use.

The narrow rigid rack components referred to are designated 46 and these are positioned each adjacent to a side edge of the board 44 to extend parallel to such edge and from the bottom to the top edges of the board and are removably secured to the board by headed screw threaded fasteners 47, the heads of which are designated 4-7 and stand up above the rack and function as stops for the hereinafter described gear boxes.

The straight edge construction designed for use in association with the racks 46 is generally designated 43. This rack construction comprises the relatively wide blade body 49, the under face of which is slightly transversely arcualte as indicated at 49 so that the blade will contact the drawing surface lightly or in a fine line along each of the two longitudinal edges thereof and there is formed integrally with the blade on the top side the solid reinforcing rib 50 which is flat on the top 51 and has the longitudinal sides inclined or sloping inwardly as indicated at 52.. From the line of joinder between sides 52 and the body of the blade the top surface of the blade slopes so that the blade from the rib 50 extends outwardly on both sides of the rib at a taper to give a relatively thin longitudinal guiding edge 53.

The overall length of the blade rib '50 is greater than the blade body and the rib 50 at each end is undercut or transversely recessed as indicated at 54 so that there is a thin top portion of the rib, designated 55', which projects beyond the adjacent end face 56 of the blade body as shown in FIG. 10.

The rib 5% is illustrated in FIGS. 7 and I!) as being of solid construction and, of course, may be formed of any suitable material, either metal, plastic or any other substance which will serve the desired purpose. However, it is also contemplated as being within the purview of the present invention to form this rib as a tube or hollow throughout its length and in such form it may be either molded as an integral part of the blade body or separately formed and secured to the top of the blade body, as, for example, shown in FIG. 14. In this latter figmre the blade of the straight edge'is designated '74 and the top of this blade has the central longitudinal fiat and horizontal surface 75 from opposite sides of which extend the fiat downwardly inclined surfaces 76 which converge with the under side of the blade to give it the desired relatively thin longitudinal edges. The tubular reinforcement rib resting upon and extending lengthwise of the flat central top surface 75 is designated 77 and in similar fashion to the rib 26 it has the downwardly converging sides 78 which join the bottom plate or wall 79 resting upon the surface 75, while the sides 78 are joined together at the top edges by the horizontal wall thus forming the longitudinal passage 81. This passage may be utilized for the extension of thecords or cables from one end of the straight edge blade to the other in the same manner as illustrated in FIG. 2, or may be undercut in the same manner as the rib 50 of FIG. 10 for use in association with the gear box 57. Attachment of the tubular rib 77 to the top of the straight edge blade can be effected in any suitable manner, as by means of screws 82 extended through the straight edge blade from the under side thereof, as indicated.

At each end of the blade body there is located a casing or box corresponding to the box 32 and designated 57. This box is of substantial length and extends transversely of the blade and the rib is defined by a top wall 58, and inner and outer side walls 59 and 60, respectively, and end walls 61. The top wall 58 of the box has a flat or horizontal middle portion 58a which positions against the underside of the extension 55 of the reinforcing rib, as shown in FIG. 7, and this extended portion 55 has an aperture 62 therethrough for the reception of a screw or bolt 63 which passes through and is secured to the central top portion 58a of the box top Wall. The inner wall 59 of the wheel box bears against the adjacent end face 56 of the blade body and to further rigidity the structure or hold the wheel box 5'7 firmly in position, this Wall has attached thereto on both sides of the rib 50 a bracket plate 65'. These plates -64 are illustrated in FIGS. 8 and 9 as single flat strips of material which have their edges butted against the adjacent wall 59 to which they may be secured in any suitable manner as by welding or by pins, in the event that the wheel box and bracket plates are of metal, or any other suitable means may be used for attaching the bracket plates to the wheel box,

and these plates are located so that when the wheel box I is fixed in position against the underside of the extended portion 55 of the reinforcing rib and in the recess 54, the plates will lie directly upon the sloping top surfaces of the straight edge body to which they may be secured by pins passing through the plates and into the body as indicated at 65.

As an alternative to the use of the flat plates 64 there may be employed the angle brackets 66 shown in FIG. 13. These angle brackets embody the two right angularly related portions 67 and 68 and each has one portion,

here designated the portion 67, fixed against the outer side of the wall 59 in a suitable manner as by means of rivets, or welding, with the other portion, designated 68, projecting laterally to lie upon the sloping top surface of the blade body to be fixed thereto, in the same manner as the plates 64.

The parts described are so dimensioned that when the straight edge blade body is rested upon the drawing board or a sheet of paper thereon in the manner illustrated, the open underside of the wheel box 57 will have the bottom edges of the walls thereof spaced from but in close proximity to the teeth of the adjacent rack 46.

At opposite ends of the wheel box 5'7 there are located the transversely extending pivot pins 69. Each of these pivot pins has rotatably mounted thereon a toothed wheel 76% which is positioned so that the teeth will extend slightly below the bottom edges of the box for interengagement with the teeth of the rack 46. The entire straight edge construction will then be either supported by the Wheels on the racks in very close proximity to the paper or it may rest lightly on the paper, but the support given by the wheels will be sufiicient that the straight edge can be easily shifted up and down across the board for drafting purposes.

The wheels 70 have flanges 71 at their ends which overlap the adjacent sides of the supporting rack 46 and thus keep the wheels centered or against axial movement across the rack and prevent shifting of the straight edge to an extent which might cause detachment of the structure from the supporting racks.

As a further modification of the construction employing the tensioned strand elements 24- illustrated and described in connection with the first embodiment shown in FIGS. 1 to 5, inclusive, the straight edge body may be cast or molded in one piece with the reinforcing back rib, as shown in FIG. 11. In this figure, the straight edge body is generally designated 72 and the hollow or tubular reinforcing back rib is generally designated 73 and, as shown, this rib is non-detachable, as is the rib 26 shown in FIG. 5, for example.

From the foregoing it will be seen that in both of the embodiments shown in FIGS. 1 to 5 and 6 to 10 the several components making up the straight edge construction are adapted to be separated one from another and, therefore, if one component should become damaged in any manner or when it becomes worn, the entire straight edge structure will not have to be replaced but the worn or damaged component can be removed and a replacement obtained for it.

Also it will be apparent that by the present invention there is provided a simple, efiicient and satisfactory mobile drafting apparatus which can be economically manufactured and marketed; which is easy to set up for use on a drawing board and which, when once properly set up, can be used indefinitely without danger of the straight edge body becoming out of position or deranged.

I claim:

A straight edge construction for mobile drafting apparatus for use in combination with guiding elements attached to a drawing board, said construction comprising an elongate blade body of substantial Width and having parallel longitudinal drawing instrument guiding edges, said blade body having a longitudinal groove formed in its top surface and longitudinally and centrally thereof, a thin walled tubular rib open at its ends and having a longitudinal bottom portion adapted to fit in said groove, said bottom portion of the rib having oppositely projecting and longitudinally extending flanges thereon and said blade body formed at each side of the bottom portion of said groove to slidably receive said flanges, an elongate wheel housing of a length less than the width of said blade body and disposed upon the top of the blade body transversely of each end thereof and having a side wall abutting the adjacent open end of said rib member, the said side Wall of each housing having an opening corresponding to the open end of the rib member, each housing having its opposite end walls provided with openings for the passage of a guiding element, means detachably securing each housing to the blade body and each of the said openings at the opposite ends of the housings having opposite vertical edges bordered by outwardly and laterally curving flanges for functioning as chafe guards for guiding elements passing through the opening.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Dietzgen publication: The Dietzgen Premier Parallel Ruling Straight-Edge, C 247/4912/RN 70.1, Eugene Dietzgen Co., Chicago, Illinois. Received February 27, 1957. 

